Mr. Maxwell et O. Eitan, RANGE EXPANSION OF AN INTRODUCED MANTID IRIS-ORATORIA AND NICHE OVERLAP WITH A NATIVE MANTID STAGMOMANTIS-LIMBATA (MANTODEA, MANTIDAE), Annals of the Entomological Society of America, 91(4), 1998, pp. 422-429
Iris oratoria L. invaded southern California in the 1930s. We describe
its subsequent northward and eastward expansion in the southwestern U
nited States. The rate of expansion into Arizona suggests that human a
ctivities have played a part in its spread. This mantid has come into
contact with a native species Stagmomantis limbata Hahn. We present 3
Fr of field data on 2 components of niche overlap between these 2 spec
ies: overlap in habitat use over lime and in diet. At a field site in
Davis, Ck S. limbata hatched earlier in the season than did I. oratori
a, and I. oratoria tended to persist longer into the year than did S.
limbata. The diets of the species overlapped to a moderate extent, yet
they differed with respect to prey type and length. S, limbata ate a
greater proportion of orthopterans and mantids than did I. oratoria, a
nd S. limbata ate longer prey than did I. oratoria. Additionally, S. l
imbata adults had longer pronota and forelegs than I. oratoria adults.
This difference in body size might be an important cause of the dieta
ry differences between the species. Furthermore, the earlier hatch dat
e for S. limbata also might result in a reduction of size overlap and,
consequently, diet overlap among nymphs of the 2 species. Thus, the d
ifferences in body size and phenology may be mechanisms that allow the
se species to coexist.